The long range goal of this project is to improve our understanding of the function and regulation of the lens cell plasma membrane. The immediate aims of this proposal are two-fold. The first will address the question of how cell-to-cell permeability is regulated between lens fiber cells. The second aim is to define the specific associations made by lens membrane proteins which may contribute to cell integrity, provide contractile force during lens movement, and facilitate lens transparency. There is now considerable support for the concept of gap junction formation between lens cells. In addition, similar to gap junctions formed between cells in other organs, the opening/closing of these junctions may be sensitive to calcium. This has led to the proposal that calmodulin regulates the gap junction mediated cell-to-cell permeability in lens cells. This hypothesis will be tested in the first section of the project by affinity labeling purified lens cell membranes with 125I-calmodulin in the presence of crosslinking reagents. The 125I-labeled proteins will be analyzed by sodium dodecyl sulfate gel electrophoresis and radioautography. The second aim of this project is to define the nearest neighbour interactions of lens membrane proteins. This will be achieved using bifunctional crosslinking reagents. A cytosolic protein kinase phosphorylates specifically certain lens cell membrane proteins. Possible associations of 32P-protein kinase labeled membrane proteins with calmodulin and other lens membrane proteins should be revealed by this procedure. Associations between cytosolic lens cell proteins and intrinsic lens membrane proteins will also be determined in this section of the project. This section of the project should suggest a role for the many extrinsic and intrinsic proteins that have been identified in lens plasma membranes. Many manifestations of cataracts are exaggerations of changes found in the aging lens. The amount of insoluble protein increases in most forms of cataracts and the role of the lens membrane in this process remains to be explained. By defining the role of some of the lens membrane proteins, it is anticipated that this project will lead to an improved understanding of lens fiber regulation and as a result, a better basis for interpreting the nature of cataract formation.